Fluidized bed process for drying ammonium sulphate

ABSTRACT

A nozzle introducing a spray into a fluidized bed is positioned a few inches below the top of the expanded bed to minimize the production of dust and to reduce the formation of lumps of material on the surfaces of the nozzle.

llnited States Patent 1191 Ganiaris Feb. 26, 1974 [5 FLUIDHZED BED PROCESS FOR DRYING 2,895,800 7/1959 Otto 23 302 AMMQNHUM SULPHATE 2,739,039 3/1956 Phelps 23/129 Inventor! w y 99mm, 3671 Hudson 3,152,005 10/1964 Tuttle 117/100 Manor Tern, Riverdale, NY. 10463 3,251,428 5/1966 Tabler 117/100 3,322,492 5/1967 Flood 23/46 [221 Flled: June 141 1971 3,340,333 /1967 Nadler 23 91 2 Appl No: 152 7 3,578,396 5/1971 Priestley 162/30 9 2,789,034 4/1957 Swaine et a1... 23/177 Fdreign Application Priority Data Primary Examiner jack sofer June 13, 1970 Great Britain 28721/ [52] 11.5. C1 159/48 R, 423/545, 159/D1G. 3 [57] ABSTRACT [51] Int. Cl 0010 1/16, F26b 3/12 [58] Field of Search H l59/DIG 3 48 R; 423/545; A nozzle mtroducmg a spray mm a flu1d1zed bed 1s po- 117 00 A sitioned a few inches below the top of the expanded bed to minimize the production of dust and to reduce [56] References Cited the formation of lumps of material on the surfaces of UNITED STATES PATENTS the 2,805,125 9/1957 Van Ackeren 23/302 1 Claim, 3 Drawing Figures kg .901 L/T/O/V 0F 25 5? @2504 ;I B. O 911-27010 fl- Q Ql 1; 1 M 2' 1 P4 20 PRODUCT f7 'l' M l FLUIDIZED BED PROCESS FOR DRYING AMMONIUM SULPHATE BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal, vertical section through a fluidized bed apparatus showing a pipe nozzle positioned within the expanded bed;

FIG. 2 is a section taken on line 2-2 of FIG. 1; and

' FIG. 3 is a longitudinal, vertical section through a fluidized bed apparatus showing a conventional spray nozzle positioned below the top of the fluidized bed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS LII upwards through the perforated plate 17 to form the I fluidized bed 18. Hot gases leave through duct and a product is withdrawn through pipe 20.

If the apparatus is a granulator, nozzle 22 has a solution introduced into it through fitting 23 to spray into the bed 18 through the apertures 24. Nozzle 22 may have a peaked or pointed cover 25 fixed over it.

The placing of nozzle 22 within bed 18 has two main advantages. First, the solution sprayed from nozzle 22 directly enters bed 18 so that it cannot escape without coating the fluidized particles of the bed. When the solution is sprayed from above the bed as in conventional practice, water may evaporate from some small droplets before they can aggregate with fluidized particles so that the droplets become dust which is carried out duct 19. This may require the costly collection of quantities of dust which then must be recycled or wasted.

Second, many materials being granulated will lump or stick and build up on any surfaces that are provided. By locating the nozzle 22 within the bed, the violently moving fluidized particles of the bed will constantly im pinge on the nozzle 22 and dislodge any particles sticking to it to prevent the buildup of large lumps which could clog the product exit pipe 20.

FIG. 3 shows a blower 30 passing air through duct 31 to a gas fired heater 32. Hot gases from heater 32 pass through duct 33 to the base 34 of the fluidized bed container 35. The hot gases pass upwards through a perforated plate 36 to form the fluidized bed 37 in container 35. Gases leave container 35 through duct 39 and product is withdrawn through pipe 40. Nozzle 41 may be any conventional spray device fixed at the end of pipe 42 through which solution is introduced. As has been stated, this location of nozzle 41 reduces the production of dust or fines and prevents the formation of lumps on the surfaces of nozzle 41. This invention has been used successfully in the granulation of a 42 to 48 per cent solution of ammonium sulfate to form solid particles or pellets of a desired size.

What is claimed is:

1. In a process of introducing a feed of 42 to 48 percent solution of ammonium sulfate into a fluidized bed, the step of injecting the feed as a plurality of downwardly directed jets extending along an entire diameter of the bed and submerged in the bed below the upper surface of the bed; wherein the bed granulates the solution into solid particles and is fluidized by an upwardly directed flow of hot air and combustion products as a drying gas extending across the entire bottom of the bed. 

